The present invention relates to a thermoplastic elastomer composition that will provide little load on the environment and to a method for producing the same.
Olefin-based thermoplastic elastomer compositions have been used for various components typified by automotive interior parts, such as console boxes and instrument panel overcoatings, and automotive exterior parts, such as window moldings because they can be processed by means of molding machines in use for ordinary thermoplastic resins and they are recyclable and flexible (see JP-A-6-136205).
On the other hand, the environmental pollution caused by the dumping of plastics and the global warming caused by the gas emitted at the time of the incineration of plastics have recently become problems. Under such situations, for example, polylactic acid obtainable by polymerizing lactic acid produced by fermenting starch or the like has attracted attention as a biodegradable plastic or a carbon-neutral material.
However, since only low impact resistance can be achieved by a polylactic acid alone under the present circumstances, it is difficult to substitute for conventional petroleum source-derived resins. In order to impart impact resistance to a polylactic acid-based polymer, a method that comprises adding a rubber (see WO 2008/026632 A) and a method that comprises adding a thermoplastic resin and a graft copolymer (see JP-A-2005-320409) have been proposed.
There have heretofore been developed various environmentally friendly plastics using non-petroleum source-derived materials. Many of such plastics, however, are inferior in mechanical characteristic, rubber elasticity, and the like and therefore their field of application has been limited.